1. Field of the Invention
This invention relates to an image forming device such as a copying machine, and more particularly to a framed-area defining rectangle forming device for forming a frame surrounding a specified area into a rectangular shape in an original image in which the area is specified by the frame of halftone or color indicated by use of a marker pen or the like and providing rectangle information.
2. Description of the Related Art
In some devices such as DPPC for reading and processing an image in a digital form, an area specified in a freely defined shape by use of a marker pen (or felt pen) on the original can be recognized. When the specified area is processed as an area of freely defined shape, no problem occurs in the real-time simple edition which does not use a page memory or the like, but the process becomes complicated in the edition such as rotation or movement using a page memory or the like. Therefore, as is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 3-17787, a method of recognizing a frame of freely defined shape indicated by use of a marker pen and fetching the recognized area as rectangle information is proposed and put into practice. In the case of this device, an area surrounded by the frame is detected, the detected area is determined as a framed area and formed into a rectangular shape, and various rectangular application editions such as centering, cornering and framing are effected.
Various methods of holding the rectangle information can be considered, but in any case, the coordinate values of two points in the x-axis and y-axis directions are necessary for each rectangle information item and a register used for automatically storing the coordinate values is necessary. Since the register is required to have a large capacity for each rectangle, the number of registers used is limited. When an area surrounded by a marker is formed into a rectangular shape as described before and if a noise component is introduced into the rectangle forming circuit, the noise portion is also treated as part of a rectangular area and it becomes impossible to obtain information of the rectangular area which is originally necessary.